Evaluation of James Lip Pressure Method for Low Flow Rate Geothermal Well: ML-5 Case Study

Abstract

Currently, there are six exploration wells in Muara Laboh field. One of these wells where James lip pressure method has been applied is ML-5. The interesting feature of this well is the low flow rate characteristic that has been demonstrated after drilling. This feature is suspected to have influenced the accuracy of James lip pressure method. Beside James lip pressure method, other intensive well testing surveys had been conducted at ML-5 during flow performance test, including tracer flow test (TFT). The TFT is a reliable method able to give accurate analysis for flowing enthalpy and mass flow rate of geothermal wells. The work is accomplished to evaluate the accuracy of James lip pressure method for ML-5. Results of the method are analyzed and compared to the results of TFT method. Possibilities of error are identified. Several aspects that may contribute to the errors are elaborated. The correction process is conducted and sensitivity analysis is performed. Case of ML-5 shows that relative error of James lip pressure method falls in a 10 – 14 % error margin relative to the result of TFT method. The work clearly demonstrates that accuracy of the method is very sensitive to the measurements on brine water level at the weir box. Further investigation shows that it is still possible to maintain the accuracy in the range of ± 2 % error margin by improving the measurement on brine water level at the weir box. Furthermore, the work also suggests that TFT survey is important as benchmarking to guarantee the reliability and accuracy of James lip pressure measurement.